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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * arch/alpha/lib/strchr.S
4 * Contributed by Richard Henderson (rth@tamu.edu)
5 *
6 * Return the address of a given character within a null-terminated
7 * string, or null if it is not found.
8 */
9#include <linux/export.h>
10#include <asm/regdef.h>
11
12 .set noreorder
13 .set noat
14
15 .align 3
16 .globl strchr
17 .ent strchr
18strchr:
19 .frame sp, 0, ra
20 .prologue 0
21
22 zapnot a1, 1, a1 # e0 : zero extend the search character
23 ldq_u t0, 0(a0) # .. e1 : load first quadword
24 sll a1, 8, t5 # e0 : replicate the search character
25 andnot a0, 7, v0 # .. e1 : align our loop pointer
26 or t5, a1, a1 # e0 :
27 lda t4, -1 # .. e1 : build garbage mask
28 sll a1, 16, t5 # e0 :
29 cmpbge zero, t0, t2 # .. e1 : bits set iff byte == zero
30 mskqh t4, a0, t4 # e0 :
31 or t5, a1, a1 # .. e1 :
32 sll a1, 32, t5 # e0 :
33 cmpbge zero, t4, t4 # .. e1 : bits set iff byte is garbage
34 or t5, a1, a1 # e0 :
35 xor t0, a1, t1 # .. e1 : make bytes == c zero
36 cmpbge zero, t1, t3 # e0 : bits set iff byte == c
37 or t2, t3, t0 # e1 : bits set iff char match or zero match
38 andnot t0, t4, t0 # e0 : clear garbage bits
39 bne t0, $found # .. e1 (zdb)
40
41$loop: ldq t0, 8(v0) # e0 :
42 addq v0, 8, v0 # .. e1 :
43 nop # e0 :
44 xor t0, a1, t1 # .. e1 (ev5 data stall)
45 cmpbge zero, t0, t2 # e0 : bits set iff byte == 0
46 cmpbge zero, t1, t3 # .. e1 : bits set iff byte == c
47 or t2, t3, t0 # e0 :
48 beq t0, $loop # .. e1 (zdb)
49
50$found: negq t0, t1 # e0 : clear all but least set bit
51 and t0, t1, t0 # e1 (stall)
52
53 and t0, t3, t1 # e0 : bit set iff byte was the char
54 beq t1, $retnull # .. e1 (zdb)
55
56 and t0, 0xf0, t2 # e0 : binary search for that set bit
57 and t0, 0xcc, t3 # .. e1 :
58 and t0, 0xaa, t4 # e0 :
59 cmovne t2, 4, t2 # .. e1 :
60 cmovne t3, 2, t3 # e0 :
61 cmovne t4, 1, t4 # .. e1 :
62 addq t2, t3, t2 # e0 :
63 addq v0, t4, v0 # .. e1 :
64 addq v0, t2, v0 # e0 :
65 ret # .. e1 :
66
67$retnull:
68 mov zero, v0 # e0 :
69 ret # .. e1 :
70
71 .end strchr
72 EXPORT_SYMBOL(strchr)